feat: always set CI=true for subprocesses

As noted in #43761, we had recently set `CI=true` for the Renovate and
Containerbase orgs on Mend-hosted apps due to a pnpm v11 requirement:

    ERR_PNPM_ABORTED_REMOVE_MODULES_DIR_NO_TTY  Aborted removal of
      modules directory due to no TTY

    If you are running pnpm in CI, set the CI environment variable to
      "true", or set "confirmModulesPurge" to "false".

Similarly in #43606, it was noted that we should do this for `mise lock`
to mark the workspace as "trusted".

Although we went with a different situation, there will be cases where
this is useful for tools being executed, for instance when we invoke `yarn`.

We also make sure to keep our documentation up-to-date as we add to the
specific overrides.

Author: jamietanna

docs/usage/environment-variable-handling.md

@@ -27,6 +27,10 @@ By default, Renovate will **always** pass the following environment variables to
 
 <!-- Autogenerate basicEnvVars -->
 
+Additionally, Renovate will **always** set the following environment variables to these exact values:
+
+<!-- Autogenerate hardcodedProcessEnv -->
+
 !!! note
   Some managers pass additional environment variables where necessary.
   <br>

lib/util/exec/env.spec.ts

@@ -1,5 +1,9 @@
 import { GlobalConfig } from '../../config/global.ts';
-import { getChildProcessEnv } from './env.ts';
+import {
+  basicEnvVars,
+  getChildProcessEnv,
+  hardcodedProcessEnv,
+} from './env.ts';
 
 describe('util/exec/env', () => {
   const envVars = [
@@ -51,7 +55,25 @@ describe('util/exec/env', () => {
       'PROGRAMFILES(X86)': 'PROGRAMFILES(X86)',
       APPDATA: 'APPDATA',
       LOCALAPPDATA: 'LOCALAPPDATA',
+
+      CI: 'true',
+    });
+  });
+
+  it('always sets static values for CI', () => {
+    expect(getChildProcessEnv()).toMatchObject({
+      CI: 'true',
+    });
+  });
+
+  it('static environment variables override the process environment variables', () => {
+    process.env.CI = 'false';
+
+    expect(getChildProcessEnv()).toMatchObject({
+      CI: 'true',
     });
+
+    delete process.env.CI;
   });
 
   it('returns environment variable only if defined', () => {
@@ -81,4 +103,22 @@ describe('util/exec/env', () => {
       expect(getChildProcessEnv()).toMatchObject(process.env);
     });
   });
+
+  describe('basicEnvVars and hardcodedProcessEnv should not have any overlap', () => {
+    describe('basicEnvVars does not include any environment variables in hardcodedProcessEnv', () => {
+      for (const env of Object.keys(hardcodedProcessEnv)) {
+        it(`${env} is not in basicEnvVars`, () => {
+          expect(basicEnvVars).not.toContain(env);
+        });
+      }
+    });
+
+    describe('hardcodedProcessEnv does not include any environment variables in basicEnvVars', () => {
+      for (const env of basicEnvVars) {
+        it(`${env} is not in hardcodedProcessEnv`, () => {
+          expect(hardcodedProcessEnv).not.toContainKey(env);
+        });
+      }
+    });
+  });
 });

lib/util/exec/env.ts

@@ -2,7 +2,6 @@ import { GlobalConfig } from '../../config/global.ts';
 import { regEx } from '../regex.ts';
 
 export const basicEnvVars = [
-  'CI',
   'HTTP_PROXY',
   'HTTPS_PROXY',
   'NO_PROXY',
@@ -49,6 +48,10 @@ export const basicEnvVars = [
   'PNPM_MAX_WORKERS',
 ] as const;
 
+export const hardcodedProcessEnv: Readonly<NodeJS.ProcessEnv> = {
+  CI: 'true',
+} as const;
+
 export function getChildProcessEnv(
   customEnvVars: string[] = [],
 ): NodeJS.ProcessEnv {
@@ -69,5 +72,10 @@ export function getChildProcessEnv(
       env[key] = process.env[key];
     }
   }
+
+  for (const [key, value] of Object.entries(hardcodedProcessEnv)) {
+    env[key] = value;
+  }
+
   return env;
 }

lib/util/exec/index.spec.ts

@@ -1137,6 +1137,7 @@ describe('util/exec/index', () => {
           'PATH',
           'LC_ALL',
           'LANG',
+          'CI',
         ],
       },
       'Executing command',

test/exec-util.ts

@@ -75,6 +75,7 @@ export function mockExecSequence(execResults: ExecResult[]): ExecSnapshots {
 }
 
 const basicEnvMock = {
+  CI: 'true',
   HTTP_PROXY: 'http://example.com',
   HTTPS_PROXY: 'https://example.com',
   NO_PROXY: 'localhost',

tools/docs/env-vars.ts

@@ -1,4 +1,4 @@
-import { basicEnvVars } from '../../lib/util/exec/env.ts';
+import { basicEnvVars, hardcodedProcessEnv } from '../../lib/util/exec/env.ts';
 import { readFile, updateFile } from '../utils/index.ts';
 import { replaceContent } from './utils.ts';
 
@@ -11,12 +11,26 @@ function basicEnvVarsToMarkdown(): string {
   return `${list}\n\n`;
 }
 
+function hardcodedProcessEnvToMarkdown(): string {
+  const list = Object.keys(hardcodedProcessEnv)
+    // case-insensitive sort
+    .sort((a, b) => a.localeCompare(b, undefined, { sensitivity: 'base' }))
+    .map((k) => ` - \`${k}=${hardcodedProcessEnv[k]}\``)
+    .join('\n');
+  return `${list}\n\n`;
+}
+
 export async function generateEnvVars(dist: string): Promise<void> {
   let content = await readFile('docs/usage/environment-variable-handling.md');
   content = replaceContent(
     content,
     basicEnvVarsToMarkdown(),
     '<!-- Autogenerate basicEnvVars -->',
   );
+  content = replaceContent(
+    content,
+    hardcodedProcessEnvToMarkdown(),
+    '<!-- Autogenerate hardcodedProcessEnv -->',
+  );
   await updateFile(`${dist}/environment-variable-handling.md`, content);
 }